The present invention is in the field of processes for making surfactants useful in cleaning products. Preferred processes comprise particular combinations of adsorptive separation steps to separate certain hydrocarbons using specific means. Preferably these means include combinations of two or more particular adsorbent beds and two or more of particular types of rotary valves, as well as specified types of porous adsorbents having pore sizes in excess of those used in conventional linear alkylbenzene manufacture. Preferred processes further employ particular alkylation steps having specified internal isomer selectivities. The invention is also in the field of products of such processes, including certain modified alkylbenzenes, of modified alkylbenzenesulfonate surfactants, and of consumer cleaning products, especially laundry detergents, containing them. Preferred processes herein employ unconventional sequences of adsorptive separation steps to secure certain branched hydrocarbon fractions which are then used in additional process steps as alkylating agents for arenes or for other useful surfactant-making purposes. Surprisingly, such fractions can even be derived from effluents from current linear alkylbenzene manufacture.
Historically, highly branched alkylbenzenesulfonate surfactants, such as those based on tetrapropylene (known as xe2x80x9cABSxe2x80x9d or xe2x80x9cTPBSxe2x80x9d) were used in detergents. However, these were found to be very poorly biodegradable. A long period followed of improving manufacturing processes for alkylbenzenesulfonates, making them as linear as practically possible (xe2x80x9cLASxe2x80x9d). The overwhelming part of a large art of linear alkylbenzenesulfonate surfactant manufacture is directed to this objective. Large-scale commercial alkylbenzenesulfonate processes in use in the U.S. today are directed to linear alkylbenzenesulfonates. However, linear alkylbenzenesulfonates are not without limitations; for example, they would be more desirable if improved for hard water cleaning properties.
In the petroleum industry, various processes have recently been developed, for example for producing low viscosity lube oil or high-octane gasoline, which the inventors have now found provide useful new insight on how to delinearize hydrocarbons to a limited and controlled extent. Such deliberate delinearization, however, is not a feature of any current commercial processes in the different field of alkylbenzenesulfonate surfactant manufacture for consumer products. This is not surprising, in view of the overwhelming volume of LAS surfactant art teaching toward making linear compounds and away from delinearization.
The majority of commercial processes for making alkylbenzenes rely on HF or aluminum chloride catalyzed alkylation of benzene. Quite recently, it has been discovered that certain zeolite catalysts can be used for alkylation of benzene with olefins. Such a process step has been described in the context of otherwise conventional processes for manufacture of linear alkylbenzenesulfonates. For example, the DETAL(copyright) process of UOP uses a zeolite alkylation catalyst. The DETAL(copyright)) process and all other current commercial processes for alkylbenzenesulfonate manufacture are believed to fail to meet the internal isomer selectivity requirements of the preferred inventive process and alkylation catalyst defined hereinafter. Moreover, the DETAL(copyright) process catalyst or catalysts are believed to lack the moderate acidity and intermediate pore size of alkylation catalysts used in the preferred processes of the present invention. Other recent literature describes the use of mordenite as an alkylation catalyst, but no such disclosure makes the combination of specific process steps required by the instant invention. Moreover, in view of the linearity desired in alkylbenzenesulfonate products of conventionally known processes, they also generally include steps directed to the provision or making of a substantially linear hydrocarbon, not a delinearized one, prior to the alkylation. Possible exceptions are in U.S. Pat. No. 5,026,933 and 4,990,718. These and other known processes have numerous shortcomings from the standpoint of the detergent industry in terms of cost, catalyst limitations in the propylene oligomerization or olefin dimerization stage, presence of large volumes of distillation fractions that would need to be discarded or find nondetergent customers, and limited range of product compositions, including mixtures of chainlengths attainable. Such developments by the petroleum industry are, in short, not optimal from the standpoint of the expert formulator of detergent products.
It is also known in the art to make linear alkylbenzenes using particular adsorptive separation processes. See U.S. Pat. No. 2,985,589. Such processes as described hitherto however do not provide branched alkylbenzenesulfonates.
It is also known in the art to prepare long-chained methyl paraffins for use as industrial solvents by processes which include urea clathration and separation on xe2x80x9cmolecular sievesxe2x80x9d. See Chemical Abstracts, 83:100693 and JP 49046124 B4. This process assertedly involves double urea adduction, for example treating a petroleum fraction once with urea to remove n-alkanes as complexes, and then a second time with excess urea to obtain adducts of mixed n-alkanes and long-chained monomethyl paraffins. While this process may have some limited usefulness and may be included in the overall processes of the invention as most broadly defined, its limitations are considerable. This process, despite dating from 1974, is not known to have been incorporated into any overall process for making surfactants such as the modified alkylbenzenesulfonates described herein.
U.S. Pat. No. 2,985,589; Chemical Abstracts, 83:100693; JP 49046124 B4 Dec. 7, 1974; EP 559,510 A Sep. 8, 1993; EP 559,510 B1 Jan. 24, 1996; U.S. Pat. Nos. 5,026,933; 4,990,718; 4,301,316; 4,301,317; 4,855,527; 4,870,038; 2,477,382; EP 466,558, Jan. 15, 1992; EP 469,940, Feb. 5, 1992; FR 2,697,246, Apr. 29, 1994; SU 793,972, Jan. 7, 1981; U.S. Pat. Nos. 2,564,072; 3,196,174; 3,238,249; 3,355,484; 3,442,964; 3,492,364; 4,959,491; WO 88/07030, Sep. 25, 1990; U.S. Pat. Nos. 4,962,256, 5,196,624; 5,196,625; EP 364,012 B, Feb. 15, 1990; U.S. Pat. Nos. 3,312,745; 3,341,614; 3,442,965; 3,674,885; 4,447,664; 4,533,651; 4,587,374; 4,996,386; 5,210,060; 5,510,306; WO 95/17961, Jul. 6, 1995; WO 95/18084; U.S. Pat. Nos. 5,510,306; 5,087,788; 4,301,316; 4,301,317; 4,855,527; 4,870,038; 5,026,933; 5,625,105 and 4,973,788 are useful by way of background to the invention. Cited documents EP 559,510 A and B in particular relate to making high-octane gasolines by recycling streams to an isomerization reactor. Grafted porous materials of EP 559,510 and grafting of zeolites, e.g., by tin alkyls, are useful in the present invention. U.S. Pat. No. 5,107,052 likewise relates to improving octane ratings of gasoline and describes separating C4-C6 methyl paraffins using various molecular sieves such as AlPO4-5, SSZ-24, MgAPO-5 and/or MAPSO-5 containing less than 2% water. These sieves are assertedly capable of selectively adsorbing dimethyl paraffins and not adsorbing monomethyl and normal paraffins.
The manufacture of alkylbenzenesulfonate surfactants has recently been reviewed. See Vol. 56 in xe2x80x9cSurfactant Sciencexe2x80x9d series, Marcel Dekker, New York, 1996, including in particular Chapter 2 entitled xe2x80x9cAlkylarylsulfonates: History, Manufacture, Analysis and Environmental Propertiesxe2x80x9d, pages 39-108 which includes 297 literature references. This work provides access to a great deal of literature describing various processes and process steps such as dehydrogenation, alkylation, alkylbenzene distillation and the like. See also xe2x80x9cDetergent Alkylatexe2x80x9d in Encyclopedia of Chemical Processing and Design, Eds. Mc. Ketta and Cunningham, Marcel Dekker, N.Y., 1982., especially pages 266-284. Adsorption processes such as UOP""s Sorbex process and other associated processes are also described in Kirk Othmer""s Encyclopedia of Chemical Technology, 4th. Edition, Vol. 1, see xe2x80x9cAdsorption and Liquid Separationxe2x80x9d, including pages 583-598 and references cited therein. See also publications by UOP Corp., including the xe2x80x9cProcessing Guidexe2x80x9d available from UOP Corp., Des Plaines, Ill. Commercial paraffin isolation and separation processes using molecular sieves include MOLEX(copyright) (UOP Inc.), a liquid-phase process, and ISOSIV(copyright) (Union Carbide Corp.) as well as ENSORB(copyright) (Exxon Corp.) and TSF(copyright) or Texaco Selective Finishing process, which are vapor-phase processes. All these processes are believed to use 5 Angstrom molecular sieves as porous media. Where not noted herein, the operating temperatures, pressures and other operating conditions and apparatus for any process step are conventional, that is, as already well known and defined in the context of manufacturing linear alkylbenzenesulfonate surfactants. Documents referenced herein are incorporated in their entirety.